Pump



y 1951 A. A. WAGNER ETAL 2,983,228

PUMP

Filed Jan. 26 1959 United States Patent PUMP Anthony A. Wagner and Robert C. Wyth, Cedar Falls, Iowa, assignors to Viking Pump Company, Cedar Falls, Iowa, a corporation of Iowa Filed Jan. 26, 1959, Ser. No. 788,952

1 Claim. (Cl. 103-426) The present invention relates generally to positive displacement pumps of the internal-external gear type and, more particularly, it relates to means for improving the working efficiency of internal-external gear pumps.

Internal-external gear pumps are well known and have been used for many years. These pumps comprise a pair of intermeshing, coacting gears which positively pump fluids. An external gear rotates within a pump chamber or casing and an internal gear, which is out of concentricity with the external gear, interengages and disengages in the operation to effect the pumping action. Because of sizeable pressures which can develop in the operation of the internal-external gear pump, the external gear tends to be forced against the periphery of the pump chamber thereby causing a degree of wear which impairs the efficiency of the pump. In this connection, leakage between the external gear and the casing results in substantial pressure losses and, as indicated, substantially reduces the efiiciency of the pump. This wear is not necessarily uniform around the periphery of the chamber and, therefore, the internal configuration of the housing may be changed from its cylindrical original form.

It is a principal object of this invention to provide an improved pump of the internal-external gear type.

It is a further object of this invention to-provide selfcompensating or adjusting means for wear which occurs in internal-external pumps. It is a still further object of this invention to provide improved self-adjusting means for wear occurring in internal-external gear type pumps.

Further objects and advantages of the invention will become apparent by reference to the following description and drawings.

In the drawings:

Figure 1 is a side elevational view, partially in crosssection, of the improved internal-external gear pump of the invention.

Figure 2 is an end elevational view, partially in crosssection, taken along line 2-2 in Figure 1.

The external-internal gear type pump of this invention comprises a pumping chamber housing 5 in which are disposed an external gear 7 which meshes with an eccentrically positioned internal gear 9.

The pumping chamber housing 5 may be cast or otherwise manufactured from suitable materials. The housing comprises a head section 6 and a cover plate 8 which is bolted to the head section 6. The head section 6 connects with an inlet well 10 which communicates through a port 11 to an inlet pipe 13. The port 11 may be threaded to engage the pipe 13. In order to provide access to the inlet chamber 10 and for cleaning purposes, an opening 15 is tapped in the pumping chamber housing 5 to receive a removable plug 17.

The head section 6 also connects with an outlet well 19 which communicates through an outlet port 21 to a discharge pipe 23. As in the case of the inlet port 11, the outlet port 21 may be threaded to receive the pipe 23. The outlet well 19 is tapped to provide an opening 25 to receive an access plug 27 for operational purposes.

The head section 6 is generally circular in cross-section (Figure 1) for receiving the external gear 7 which rotates within the pumping chamber housing 5'.

The head section 6 of the pumping chamber housing 5 is also provided with a shaft receiving section 28 through which extends a drive shaft 29 for the external gear 7. In the shaft receiving section is provided a sleeve bearing 31 and a ball bearing 33 located axially rearwardly of the sleeve bearing. The ball bearing 33 is held in position by means of a spring washer 35 which is carried in a circular slot 37 located at the end of the shaft receiving section 28. The ball bearing 33 is pressed against the spring washer 35 by means of a spring biased mechanism, of a standard arrangement, designated 39. The spring biased mechanism engages a shoulder 41 on the shaft 29.

The pumping chamber housing 5 includes a stand or base 42 which is, in the illustrated embodiment, integral with the housing, the stand 42 connecting to the head section 6 through a web 43.

The cover plate 8 of the pumping chamber housing 5 may also be cast or otherwise manufactured and is secured to the head section 6 by means of bolts 44. The cover plate 8 supports a stub shaft 45 on which is journalled the internal gear 9 in an eccentric position relative to the external gear 7, as is best shown in Figure 1 of the drawings. The internal gear 9 is an idler gear which is driven by the external gear 7, as will become more clear hereinafter.

In order that the inlet pressures shall be restricted to the face portions of the external gear 7 adjacent the inlet port, means are provided on the cover plate 8 for so restricting the inlet pressures. In the illustrated embodiment, this means also restricts the outlet pressures to those face portions of the external gear adjacent the outlet port. As shown in the drawings, this means comprises a cresent shaped segment or barrier 47 which extends between the internal gear 9 and the external gear 7 to efiect the desired restricttion of pressures. This cresent shaped section is integral with the cover plate 8, as is shown in both figures of the drawings. This segment 47 is conventionally used in external-internal gear pumps and need not be further described herein.

The internal gear 9, as previously pointed out, is in an eccentric position relative to the external gear 7 and is journalled on the stub shaft 45 mounted on the cover plate 8 of the pumping chamber housing 5. The internal gear is provided with teeth 49 which are shaped and proportioned to suitably engage the external gear 7.

The external gear 7 is keyed to the drive shaft 29 and is driven thereby. The external gear 7 is provided with inwardly extending gear teeth 51 which engage the teeth 49 of the internal gear 9. The teeth 51 of the external gear also extend axially of the head section 6 of the pumping chamber housing 5 and, at their base, the teeth are adjacent the periphery of the head section 6. Because of normal operating conditions, the teeth of the external gear 7 engage the periphery of the head section 6 and wear away portions of the head section 6. This eflect is generally illustrated in Figure 1 wherein wear of the head section 6 is shown generally between the 3 oclock and 9 oclock positions. If this wear is not compensated by suitable means, there is loss of pressure in the pump which results in quite substantial inefiiciency. In order to limit loss of these pressures, the invention provides self-adjusting means on the gear teeth 51 of the external gear 7 which extend between these teeth to the head section 6 to thereby compensate for wear which may occur.

In the illustrated embodiment of the invention, this self-adjusting means comprises vanes 53, which extend axially. These vanes arereceived in slots 55, which also extend axially, in the gear teeth 51 of the external gear 7. The vanes 53 are proportioned to permit radial movement of the vanes from the gear teeth 51 toward the periphery of the head section 6 of the pumping-chamber housing 5. Of course, centrifugal forces resulting from the rotation of the external gear 7 cause the vanes 53 to engage the periphery of the head section 6.

In order to permit free movement of the vanes radially outward, pressure equalizing means are provided to the slots 55 in the gear teeth 51 of the external gear 7. In the illustrated embodiment, pressure equalizing means comprises ports 57 which extend from the slots 55 through the teeth 51 of the external gear 7 into an internal point' in the pumping chamber housing 5. Through these ports 57 any relative vacuum established in the slots 55 upon outward movement of the vanes 53 is relieved thereby assuring free movement of the vanes against the periphery of the head section 6 of the housing 5. This is an important feature of the invention to provide most etlicient operation. This feature becomes particularly important when higher viscosity fluids are to be pumped.

In operation of the external-internal gear type pump of this invention, the material which is to be pumped enters the inlet pipe 13 and passes into the inlet well 10. Through coaction of the internal-gear 9 and the external gear 7, the material is pumped at a higher pressure out of the outlet pipe 23. As the external gear 7 wears against the internal periphery of the pumping chamber housing 5, the self-adjusting means of the invention eifectively operates to prevent-loss in pressure between the external gear 7 of the head section 6. In operation, the vanes '53 of the self-adjusting means move outwardly against the periphery of the head section 6 and the free outward movement of these vanes is assured by means of the ports 57 in the gear teeth 51 of the external gear 7.

The various features of this invention which are believed to be new are set forth in the following claim.

We claim:

In an external-internal gear type pump including a hous: ing having a generally cylindrical pumping chamber with spaced apart inlet and outlet ports, an external gear rotatably mounted in the chamber and having a series of inwardly projecting teeth, the teeth of the external gear having outwardly facing surfaces forming portions of an imaginary cylinder having a diameter corresponding generally to that of the cylindrical wall of the chamber, means for rotating the external gear, an internal gear rotatably mounted within the chamber on a shaft eccentrically located with respect to the external gear, the internal gear being of smaller diameter than the external gear and having a series of outwardly projecting teeth intermeshed with the inwardly projecting teeth of the external gear to prevent passage of fluid therebetween'in an area between the inlet and outlet ports, and a crescent shaped barrier located intermediate the external gear and internal gear in the area'between the inlet and outlet ports diametrically opposite to the area of intermeshing engagement of the internal gear and external gear, the improvement comprising radially extending slots in the outward-1y facing surfaces of said teeth, means movable within said slots radially of said external gear into engagement with the cylindrical wall of the chamber to prevent fluid leakage between said external gear and the chamber, and conduit means extending through said teeth in said external gear from said slots to the inwardly facing surface of said teeth.

References Cited in the file of this patent UNITED STATES PATENTS 1,009,759 Liston et a1 Nov. 28, 1911 1,407,496 Storey Feb. 21, 1922 1,665,120v Wendell V Apr. 3, 1928 1,840,869 Rayburn Jan. 12, 1932 1,990,750 Pigott Feb. 12, 1935 1,993,721 Pigott Mar. 5, 1935 2,270,222 Rea et al. Ian. 13, 1942 2,291,354 Sibley July 28, 1942 2,336,294 Rea Dec. 7, 1943 2,760,438 Hill Aug. 28, 1956 FOREIGN PATENTS 394,985 Great Britain July 5, 1933 

